An electronic device such as a computer chip can be ruined if exposed to excessive heat. Several heat dissipating systems have been used to eliminate the heat which is necessarily generated in any integrated circuitry. Forced air convection is one method of heat dissipation which has proven to be effective but expensive and of limited application. An alternative method which is well known in the industry is the placement of a heat sink in heat conducting communication with the chip.
A heat sink is a device which preferably has a relatively high rate of thermal conductivity and a high heat capacity. Because of its material properties and design a heat sink is adapted to draw heat from any closely situated heat source and dissipate that heat into the surrounding environment. Conductive heat sinks are designed in various shapes and sizes, and are adapted to conform to the shape of an exposed surface of the electronic device or chip, from which heat is to be dissipated.
One type of heat sink, as shown, for example, in Hinshaw U.S. Pat. Nos. 4,884,331, and 4,879,891, provides a generally rectangular base portion with integrally formed pins or fins rising perpendicularly from the top surface of the base portion. The pins are arranged in a grid array over the entire top surface of the base portion. This heat sink has a generally flat bottom surface adapted to contact the flat exposed surface of a chip element mounted on a socket or housing.
The heat sink must be retained in conductive thermal communication with the chip during normal heating and cooling cycles as well as under substantial acceleration forces induced by shock and vibration. The problem of providing an assembly with a satisfactory retention system can be readily seen in prior expedients. See, for example, Bright et al. U.S. Pat. No. 4,716,494. It has been found that heat sinks should not be bonded or otherwise permanently secured directly to the computer chip because the different rates of thermal expansion cause the bond or even the computer chip to break. Also, removal and replacement becomes difficult and time consuming. Similarly, the heat sink should not be bonded, or otherwise permanently secured, to the chip-holding socket for similar reasons. It is easier to service a faulty chip element when access to that chip element is easily gained.
For these and other reasons, a satisfactory assembly preferably includes a retention element which removably secures the sink to the chip-holding socket. Furthermore, the retainer element itself is preferably removably secured to the socket.
Industry standards require any such assembly to dissipate minimum levels of heat and to withstand substantial shock and vibration induced loads without unintended disassembly. A successful retainer element should enhance, or at least not interfere with, the ability of the heat sink to dissipate a sufficient amount of heat to maintain the computer chip in functioning order.
Any retention system which provides for the quick and easy installation and removal of the heat sink to and from the chip-holding socket would necessarily lower the difficulty, time and expense involved in assembling and servicing and, therefore, would be beneficial. The ease of installation and removal would be enhanced by any system which would not require complicated tools, and special skills, machines or tooling.